The bottom line is clear: Our vital interests in Afghanistan are limited and military victory is not the key to achieving them. On the contrary, waging a lengthy counterinsurgency war in Afghanistan may well do more to aid Taliban recruiting than to dismantle the group, help spread conflict further into Pakistan, unify radical groups that might otherwise be quarreling amongst themselves, threaten the long-term health of the U.S. economy, and prevent the U.S. government from turning its full attention to other pressing problems. -- Afghanistan Study Group

The statement, issued by the Prime Minister’s Office, also said that
“the Iraqi government completely rejects such action and would deal with
the presence of foreign ground troops to Iraq as though their presence
were a hostile act and a violation of Iraq's national sovereignty.”
Al-Abadi also said: “The Iraqi government is committed to not allowing ground troops on Iraqi land, and it did not ask any party, neither regional or from the coalition forces, to deploy ground forces in Iraq.”

The PM's sentiments aside, there is a widespread belief among both Sunni and Shiite Iraqis that the U.S. secretly backs IS. "The perception among Iraqis that the United States is somehow in cahoots
with the militants it claims to be fighting appears, however, to be
widespread across the country’s Sunni-Shiite sectarian divide, and it
speaks to more than just the troubling legacy of mistrust that has
clouded the United States’ relationship with Iraq since the 2003
invasion and the subsequent withdrawal eight years later."